brain.js
Powerful library for working with neural networks in a JavaScript environment. The project has great documentation with lots of examples that will help you get you up to speed with some machine learning techniques.
Code Libraries: Articifial Intelligence & Machine Learning
ml5
ml5.js aims to make machine learning accessible to a broad audience of artists, creative coders, and students. The library provides access to machine learning algorithms and models in the browser, building on top of TensorFlow.js with no other external dependencies.
TensorFlow.js
A WebGL accelerated, browser-based library for training and deploying machine learning models.
Deeplearn.js
Deeplearn.js is an open source hardware-accelerated library for machine intelligence. It brings performant machine learning building blocks to the web, allowing you to train neural networks in a browser or run pre-trained models in inference mode.